Malfunction detector

ABSTRACT

A malfunction detector for automatically monitoring and controlling operation of a cyclically operating machine performing one or more operations on work pieces at one or more stations. The detector is of modular construction and includes a circuit for providing a monitoring check cycle and indications that the monitoring cycle has been completed without detecting any malfunctions or that the cycle has not been initiated. Circuitry is also provided for indicating at which individual station any malfunction occurs during the monitoring cycle and for indicating if such malfunction circuitry at any station has become inoperative. Circuitry is also provided for initiating either immediate stoppage of the machine or stoppage at the end of the machine cycle in progress depending on the type of malfunction if the machine is so adapted.

United States Patent IlsI 3,656,139

Wlntrlss [451 Apr. 11, 1972 [54] MALFUNCTION DETECTOR PrimaryExaminer-John W. Caldwell [72] Inventor: George Victor Wintriss, SanDiego, Calif. Assistant Examiner-Michel-slobasky Attorney-Schiller &Pandlscio [73] Asslgnee: Industrionics Controls Inc., New York,

N-Y- [57] ABSTRACT [22] Filed: Apr. 28, 1970 A malfunction detector forautomatically monitoring and con- [21] Appl. No.: 32,702 trollingoperation of a cyclcally operating machine performing one or moreoperations on work pieces at one or more stations. The detector is ofmodular construction and includes a CCI" "340/267 R circuit forproviding a monitoring check cycle and indications that the monitoringcycle has been completed without detect- [58] Field of Search "S40/26720o/6122; 72/4; ing any malfunctions or that the cycle has not beeninitiated. 07/12 circuitry is also provided for indicating at whichindividuai station any malfunction occurs during the monitoring cycle[56] References cned and for indicating if such malfunction circuitry atany station UNITED STATES PATENTS has beome inopierative. Circuitrfyalso provided for initiating eit er imme iate stoppage o t e mac ine orstoppage at 3,319,087 5/1967 Wmtl'lSS 340/267 UX the end of the machinecycle in progress depending on the type of malfunction if the machine isso adapted.

14 Claims, 3 Drawing Figures MAIN ANO POWER IAUI LADY l gg ]/50\ gg,-MAIN STOP la l L/ l 6 i148 i@ l Le i 196 A C l i l ,52 z l I 208 192INPUT W3 l FLIP-FLOR L144 2 FLIP-FLOP 188 l 132 146 TO 177 l I. l l f I6% i581 I I I gcn 200 m- ORII/ER I MF/TIEN /30 DETECTOR E l| 24 i4 C180i /75 l (12@ f/56 E t 194 l l TO 2/2 98 ,90 a 179 FLIP-FLOP 160FLIP-FLOP l l FLIP-FLOR MACHINE j182 I 164 1 l l I| AUXILIARY f l l f i,62 l 1 1 l -l STOP 202 DRIVER Aux, l I l I CIRCUIT E E SCHMITT SCHMITTl SCHMITT l TRIGGER I TRICGER T TRIGGER 206 l l i l 34 1261 l 154j I I/236 A. c. l 166 l RElztv INPUT l OR l lMEMQRjgN (17g 2 ANW l I RslioYHOLD {125 I I76- BOUNCE I Rg/QYIPULSE {127 ,74 I CIRCUIT ll I l I l L,4l 140 I I t 122 1 l l l I I l 170 I I lieg l 720 i 38 l i -I2 l I i lAMP l AMP. I l 601 48 I I l l FROM l FROM l SWITCH 54 PROBE 40 20mm 20mmPATENTEDAPR 1 l |972 SHEET 2 nF 2 MALFUNCTION DETECTOR This inventionrelates to apparatus for detecting malfunctions and more particularly toa malfunction detector for use with various types of machinery.

One serious problem in operating various types of presses or similarmachinery having various reciprocal motions is the inability to quicklydetect and locate any malfunctions which may occur at one or more workstations of the machine. Some attempts have been made to provide faultdetectors but these have suffered from several drawbacks. Onesignificant drawback in such systems is the inability to determinewhether the machine itself is malfunctioning or that the detector has amalfunction. Another disadvantage of prior systems is that they arefixed systems having no flexible capability for accommodating differentmachines with a different number of stations to be monitored. Also, suchsystems do not necessarily indicate at exactly which stations themalfunction is occurring. Finally, these prior systems have a relativelyunsophisticated and crude approach in initiating stoppage of the machinewhen a malfunction is detected.

The malfunction detector of the present invention overcomes theseshortcomings and disadvantages of the prior art.

One object of this invention is to provide a new and improvedmalfunction detector for use with cyclically operating machines.

Another object is to provide a new and reliable malfunction detectorwhich monitors, controls and completely automates the operation ofcyclically operating machines of the type adapted to perform variousreciprocal motions including, among others, pressworking, stamping,punching, die-cutting, drilling, grinding, etc.

A more specific object is to provide a new and improved malfunctiondetector for controlling operation of a cyclically operated machine byreceiving signals from outside sensors and logically processing themtogether with internally generated logic signals.

A further specific object is to provide a malfunction detector which cannot only detect the location of machine malfunctions but can alsoprovide an indication when the detector itself is malfunctioning.

Another object of the present invention is to provide a malfunctiondetector which automatically initiates immediate stoppage of acyclically operating machine when a machine malfunction is detected.

Still another object of the present invention is to provide amalfunction detector which automatically initiates stoppage of acyclically operating machine at the end of the cycle in progress when adetector probe malfunction is detected.

Yet another object of the present invention is to provide a malfunctiondetector o modular construction with front-panel module loading for usewith cyclically operating machines wherein the detector can be adaptedto a desired number of stations to be monitored and controlled.

Another object of the present invention is to provide a malfunctiondetector that provides a visual indication to the machine operator ofthe instantaneous state of the machine at all times including thelocation of any detected machine malfunction and the failure ormalfunctioning of the detector itself.

Yet another object of the present invention is to provide a malfunctiondetector which makes use of some solid state, integrated circuitry andis designed for maximum reliability including the printed circuit boardconnections, filtering of each input for high noise rejection,protection from contact bounce and protection of each module fromaccidental high voltages.

The foregoing objects and other objects disclosed or rendered obvious inthis specification are attained by providing apparatus for automaticallymonitoring and controlling operation of a cyclically operating machineperforming one or more operations on work pieces at one or morestations, the apparatus comprising means for initiating a predeterminedcycle during which all the operations at the stations are simultaneouslymonitored; means for indicating completion of a monitoring cycle withall stations operating and continuing to run without any malfunctions;means for indicating that the predetermined monitoring cycle has notbeen properly initiated; means for indicating the station locations ofany machine malfunctions which occur during the predetermined monitoringcycle; means for indicating that the means for indicating a particularstations malfunctioning has become inoperative; and means for initiatingstoppage of the machine when any one of the above malfunction indicatingmeans gives a malfunction indication.

Further details and other advantages of the invention are provided bythe following description which is to be con sidered together with theaccompanying drawing wherein:

FIG. 1 is a perspective view of a machine embodying the presentinvention;

FIG. 2 is a perspective view on an enlarged scale of a portion ofthemachine of FIG. l; and

FIG. 3 is a block diagram of a preferred embodiment of a malfunctiondetector constructed according to this invention and used with themachine of FIG. l.

Turning now to FIG. 1, there is shown a machine or press 2 having aframe 4 which carries a ram 6 that is mounted to move down and up withrespect to a bed 8 in response to operation of an electrical motor 10which drives the ram through a shaft 12 rotatably mounted to frame 4 andconventional intermediate drive mechanism (now shown). Such intermediatemechanism is not shown since it forms no part of the present inventionand is well known in the art of presses. ln the usual case, shaft 12 isconnected to motor 10 by way of a clutch (not shown) and suchintermediate mechanism includes an eccentric mounted on shaft 12 andconnected to the ram through a connecting rod so that the ram isoperated through one complete down and up cycle for each revolution ofshaft 12. Bed 8 carries guide 16 adapted to support a workpiece 18. Theram 6 carries a tool 20 designed to operated on a workpiece supported byguide 16. The machine also includes means for stripping a finishedworkpiece from the guide 16. Such stripping means are shownschematically at 22 since it forms no part of the invention. Thework-stripper typically comprises a pneumatic or hydraulic actuater 24which is adapted to raise an ejection pin or pins (not shown) forstripping the workpiece from the guide 16. Discharge of the strippedworkpiece is achieved by means of a jet of air delivered on command byan air nozzle 26. The discharged parts fall onto a metal chute 30 whichforms an integral electrical connection with the frame 4 and whichdelivers them to a collecting receptacle 32.

ln accordance with this invention, the press is provided with means fordetecting machine malfunctions as hereinafter described. In thisconnection as seen in FIG. 2 the chute 30 is provided with a bracket 36on which is mounted a connector block 38 insulated from the pressframecarrying a resilient electrically conductive probe 40 that extendsdown to the level of the floor 42 of the chute. The floor 42 is providedwith a hole 44 located so that the probe cannot touch the floor. Theconnector has one or more terminals 46 which are coupled internally ofthe connector to the probe 40. ln the illustrated case, one of theterminals 46 is fitted with a connecting cable 48 which is insulatedfrom the press frame for coupling the probe to the malfunction detector.The chute is dimensioned so that each finished part discharged fromguide 16 must encounter and deflect the probe 40 before falling into thereceptacle 32. Each time the probe is encountered by a finished part, itis effectively electrically connected by the part to the chute which isat ground potential. Hence the probe and chute together comprise switchmeans. As an alternative measure, the connector block 38 could bereplaced by a normally open switch with an actuating arm that ispositioned like probe 40 so that the switch is closed each time and forso long as its actuating arm is displaced or deflected by a workpiece onthe chute.

Further in accordance with this invention, the shaft 12 is fitted with acam 50 having a lobe 52 whose periphery extends over a predeterminedangle. Mounted on the frame is a switch 54 having a pivotal operatingarm 56 carrying a roller 58 that rides on the periphery of the cam.Switch 54 is hereinafter termed the shuttle switch since its operationis according to the up and down or shuttle movement of ram 6. The switch54 Vis normally open but closes when the roller 58 is engaged by thelobe on cam 50, the lobe acting to cam arm 56 in a direction to closethe switch. The switch is coupled to the malfunction detector by asuitable insulated connecting cable 60. As an alternative measure,switch 54 and arm 56 could be replaced by probe 40 with the probedisposed to contact only the lobe of cam 50. Hence the probe wouldprovide a ground connection by way of cam 50 only during the period thatit is engaged by lobe 52.

Although the present invention is being described for use in conjunctionwith the press 2, it should be understood that the malfunction detectorcould be used with any number of different machines performing variouswork operations. The terms "operations or "work operations" as usedherein refer to the various operations which may be performed by themachine and includes, among other things, such motions or activities asfeeding, ejecting, stamping, transporting, inspecting, counting,cleaning etc., of the work pieces as well as such things as processtemperature control, process sensitivity to such extraneous elements aswater, chemicals, etc. It should be clear that the term operations" isused in a very broad sense to cover a wide variety of machine monitoringoperations and operations on workpieces.

ln the specific press 2 described, the workpieces must be electricallyconductive in order that probe 40 and any other such probes used withthe press may be properly actuated. However, machines operating onnon-electrically conductive materials may also be used with themalfunction detector of the present invention. Non-electricallyconductive work pieces would utilize different types of probes fromthose described in conjunction with press 2, such as for example,

fiber optic probes, airswitch probes, fluidic type probes, work pieceoverload type probes, sonic detector type probes, etc.

ln this preferred embodiment, the remainder of the malfunction detectoris mounted within a case 62, which may or may not be attached to theframe of the press. The front panel of case 62 is made up of a number ofplug-in modules each having indicator lights which serve to display thestatus of the operation of the machine and the malfunction detector aswill be hereafter described. Case 62 has terminals for connecting apower cable (not shown). Cables 48 and 60 are shown functionallyconnected to the appropriate plug-in modules of the malfunctiondetector.

Turning now to FIG. 3, the malfunction detector circuitry mounted withthe case 62 comprises several modular units labelled power module 112,main and auxiliary stop module 114, ready module 116, and go modules118, each separated by the vertical dashed lines. Each of the modulesare independent plug-in units mounted on separate printed circuit boardswith individual front panels and respective components. Each of thesemodules will now be described and then the total operation of thedetector will be described. These modules are front-loaded in the frontface of the case 62 of the detector as shown in FIG. l, and are easilyreplaced in a matter of seconds.

The ready module 116 monitors a predetermined checking or monitoringcycle during which malfunctions in the machine may be detected andvisually displayed to the machine operator. The ready module includesmeans for indicating proper initiation of the checking cycle by a readyindication and a ready failsafe indication when information is receivedthat the machine has stopped or the ready informationv becomes static.lf the ready indication is on or absent continuously for a predeterminedtime interval, a signal is initiated to stop the operation of themachine and at the same time provide a ready failsafe indication.

The ready module 116 receives an input signal from the switch 54 on line60 to generate a checking cycle which lasts during the time that theswitch 54 closes when the roller 58 is engaged by the lobe 52 on cam 50.The incoming signal from switch 54 is filtered by a filtering amplifier120 to substantially eliminate any undesired noise. The filtered signalis applied to a ready lamp 122 located on the front panel of readymodule 116 which when lit indicates that the switch 54 has closed and achecking cycle has been initiated. The filtered output signal is alsoapplied to an anti-bounce circuit 124 which ignores any contact bouncewhich might create ambiguities when the switch 54 closes. Anti-bouncecircuits are well known in the art and one such circuit which may beused with the present invention is described in an article inElectronics Circuit Designers Casebook, No. 14-7, McGraw Hill, 1969Edition.

The output from the anti-bounce circuit 124 should be applied to the gomodules 118 on lines 12S and 127 and to a Schmitt trigger 126 which isset to trigger after a predetermined continuous time interval. lf duringthis time interval the signal from circuit 124 is either on continuouslyor absent, then Schmitt rigger 126 fires. The time interval may beadjustable over a range, such as for example, from a few seconds up to aminute or more depending on the characteristics of the particularmachine with which the detector is being used. lf the signal from thecircuit 124 is present or absent for the predetermined time interval,the Schmitt trigger fires to change the state of a bistable circuitshown as flip-flop 128. The change of state of flip-flop 128 is fed toan amplifier 130 which drives a lamp 132 labeled failsafe on the frontpanel of ready module 116 which indicates the improper operation or lackof the checking cycle. The change of state of the flip-flop 128 is alsocoupled through a diode 134 to the stop module 114 via auxiliary stopline 136.

The go modules 118 are used to detect machine malfunctions at variouswork stations of the machine. The number of go modules may be variedaccording to the number of stations or operations to be monitored. Forexample, if three operations were to be monitored, three go moduleswould be used i.e., one go module for each operation being monitored.For purposes of this description assume that the only station beingmonitored is by probe 40 whose output signal is fed on cable 48 to thego module 118 immediately adjacent to the ready module 116. Howeverprobe 40 could be connected to any one of the go modules 118. Each ofthe go modules 118 is identical. The signal on cable 48 is applied to afiltering amplifier 138. The output from amplifier 138 drives a lamp 140on the front panel ofthe go module 118, which when lit indicates thatthe station has received a completed inspection signal without anymalfunctions in the cyclical operation of the machine at that station.

The output of the amplifier 138 is also applied to a detector 142. Alsoconnected to the detector 142 from lines 125 and 127 from theanti-bounce circuit 124 are ready hold and ready pulse signals. lf thedetector 142 does not detect a completed inspection signal from thestation during the checking cycle, the detector 142 causes a bistablecircuit shown as a flip-flop 144 to change its state. The change ofstate of flip-flop 144 is applied to an amplifier 146 which drives alamp 148 on the front panel of go module 118. When lamp 148 is lit itindicates that the machine work station which it is monitoring ismalfunctioning. The change of state of flip-flop 144 also causesinitiation of a signal which is connected to stopmodule 114 on a mainstop line 150 via a diode 152.

The filtered signal from amplifier 138 is also applied to a Schmitttrigger 154 which is set to trigger after a predetermined time interva]after the input from probe 40 on line 48 has become shorted or opens.This time interval may be varied and in the particular embodiment of theinvention is set to trigger approximately 8 seconds after the short oropen occurs. The output from the trigger 154 causes the state of abistable circuit shown as a flip-flop 156 to change, thereby lighting alamp 158 on the front panel of module 118 via a driving amplifier 160.The output from the flip-flop 156 when it changes state is also appliedto the main and auxiliary stop module 114 on line 136 via a diode 162.

The main and auxiliary stop module 114 is comprised of a main flipeflop163, an auxiliary flip-flop 164, a memory line driver made up of an'ORgate 166, and a reset switch 170. The flip-flop 163 receives its inputsignals from each of the flipflops 144 via diodes 152 of the go modules118 via the main stop line 150. The flip-flop 164 receives its inputsignals from flip-flop 128 via diode 134 of the ready module 116 andfrom each of the flip-flops 156 via the diodes 162 of the go modules 118on the auxiliary stop line 136. The outputs from each of the flip-flops163 and 164 are applied to the power module 112 and to a memory linedriver made up of an OR gate 166. lf` the OR gate 166 receives an inputfrom either flip-flop 163 or 164, a signal is applied on a memory line172 to inhibit the flip-flop 128 of ready module 116 and to inhibit eachof the flip-flops 144 and 156 of the go modules 118. Reset switch 170which appears as a reset'button on the front panel of module 114 has oneterminal connected to an internal power supply. When the switch 170 isclosed for a predetermined time, which in the preferred embodiment isone second, a gate 174 opens to allow the resetting of flip-flops 163and 164, flipflop 128 of ready module 116 and flip-flops 144 and 156 ofeach of the go modules 118 via a reset line 176. The signal on resetline 176 is also applied to the Schmitt trigger 126 of ready module 116and to triggers 154 of of go modules 118 to start the timing circuitsfor the operation of these triggers. The flip-flops 163 and 164, whenactivated to change state, drive lamps 173 and 175 via amplifiers 177and 179 respectively on the front panel of module 114 to indicate thatthey have changed state to initiate stoppage of the machine.

The power module 112 serves to provide the necessary power for theswitching of the load power to provide two independent output circuitsfor ON-OFF control of the machine. The power module includes a pair ofdriving circuits 180 and 182 which derive their inputs from the man andauxiliary stop module 114. Driving circuits 180 and 182 may be any oneof a number of well known such circuits in the art. An output fromflip-flop 163 is connected to driving circuit 180 while an output fromflip-flop 164 is connected to driving circuit 182. The outputs of eachof the driving circuits 180 and 182 are connected to the center taps ofprimary windings 188 and 190 of isolation transformers 184 and 186respectively. The driving circuits 180 and 182 apply DC levels to thecenter taps of primary windings 188 and 190 respectively. A.C. inputsignals from the systems power supply (not shown) are supplied viadiodes 192 to both end terminals of the primary windings 188 and 190.

Secondary windings 192 and 194 of transformers 184 and 186 respectivelyeach have one terminal connected to gate electrodes 196 and 198 oftriacs 200 and 202. Terminal 204 of triac 200 is connected to the otherterminal of secondary winding 192, and to a terminal of a shut offsolenoid or relay (now shown) in the machine. The other terminal 208 oftriac 200 is connected to a terminal ofthe shut off solenoid or relay.Terminal 206 of triac 202 is connected to the terminal of secondarywinding 194 opposite the terminal to which gate electrode 198 isconnected and to a terminal of another shut off solenoid or relay (notshown) in the machine if it is so adapted. Terminal 212 of triac 202 isconnected to a shutoff solenoid or relay (not shown) in the machine. Thetriacs 200 and 202 act as A.C. switches to provide the output signalsfor stopping cyclical operation of the machine being monitored andcontrolled. The triacs 200 and 202 are isolated from the A.C. inputsignals to transformers 184 and 186 respectively as well as all theother circuitry in power module 112.

The operation of the malfunction detector system, depicted in FIG. 3will now be described. As the machine 2 performs its cyclical operationsat its various work stations, the malfunction detector monitors andcontrols the operation. The ready module 116 receives a signal fromswitch 54 on line 60 which is applied to filtering amplifier 120. Thissignal lasts during the time that switch 54 closes when roller 58 isengaged by lobe 52 on cam 50 to provide the checking cycle. Lamp 122lights to indicate the initiation and continuous existence of thechecking cycle. The filtered signal from amplifier is also applied toSchmitt trigger 126 via anti-bounce circuit 124. lf the lamp 122 stayslit for the predetermined time interval for triggering Schmitt trigger154, the trigger fires to change the state of flip-flop 128. The changeof state of fiip-flop 128 causes lamp 132 to be lighted indicating thatthe checking cycle has not been properly completed. The change of stateof flip-flop 128 also causes auxiliary flip-flop 164 to change state,thereby causing driver 182 to apply a signal at D.C. level to the centertap of primary winding 190 of transformer 186. This induces a voltage inthe secondary winding 194 which actuates triac 202.

Assuming that probe 40 is the only work station being monitored in themachine of FIG. 1, the signal from probe 40 is fed on line 48 tofiltering amplifier 138. lf lamp 140 is lighted at any time during thechecking cycle, it indicates that the checking cycle at that station hasbeen completed and that no malfunctions have occurred in the monitoringoperation of probe 40. When the anti-bounce circuit receives thechecking cycle signal, it provides outputs on ready hold line and onready pulse line 127. The signal on line 125 is a ready hold signalwhich beings at the beginning of the checking cycle and is applied todetector 142 to establish a predetermined logic state for detector 142.When a ready pulse occurs on line 127, it causes detector 142 to changestate. lf a signal is received by amplifier 138 indicating the properoperation of probe 40, the detector changes back to its original stateand no output is applied from detector 142 to flip-flop 144. When,however, detector 142 is set by the ready pulse on line 127, if a signalis not received by amplifier 138 from probe 40 to reset it, the end ofthe ready hold signal on line 125 at the end of the checking cycleresults in an output from detector 142 being applied to change the stateof fiip-flop 144. This change of state of flip-flop 144 lights lamp 148indicating that the signal from probe 40 has been missed andsimultaneously triggers via line the main flip-flop 163 in stop module114. The change in state of flip-flop 163 causes driver 180 to apply asignal at D.C. level to the center tap of primary winding 188 oftransformer 184. This induces a voltage in the secondary winding 192which actuates triac 202.

If the input signal from probe 40 persists beyond a predetermined timeinterval because the operation of probe 40 has become shorted, Schmitttrigger 154 is triggered thereby changing the state of flip-flop 156which causes lamp 158 to be lighted. At the same time the change ofstate of flip-flop 156 applies a signal via diode 162 and line 136 toauxiliary stop flip-flop 164. Flip-flop 164 changes state initiatingdriver 182 to apply a signal at D.C. level to the center tap of primarywinding of transformer 186. The induces a voltage in the secondarywinding 194 which actuates triac 202.

Depending on the particular machine being monitored and controlled andwhether the machine is adapted with both an emergency stop and a stop atthe top of the cycle, the power module 112 has six possible modes ofoperation which will now be described. In the art, generally the termemergency stop refers to an immediate stoppage or shut off of themachine whereas a top stop refers to the machine continuing itsoperation until the end of the cycle in progress has been completedbefore it comes to a stop or shuts off. ln one mode of operation withboth triacs 200 and 202 connected independently and triac 200 connectedto the emergency stop circuit and triac 202 connected to the top stopcircuit of the machine, both triacs are normally conducting. When eitherthe main or auxiliary flip-flops 163 and 164 respectively changes state,the corresponding triac 200 and 202 is turned off, thereby actuating thecorresponding stop circuit connected to triac 200 or 202 to eitherimmediately stop the machine or to stop it when ram 6 reaches the top ofits up-down reciprocal movement.

ln a second mode of operation with both triacs connected independentlyto their respective stop circuits, both triacs are normally notconducting and a change of state of one of their correspondingflip-flops 163 and 164 will turn on the corresponding triac, therebyactuating the corresponding stop circuit. A third mode of operation hastriac 200 normally conducting and triac 202 nonnally not conducting. Achange of state of main flip-flop 163 will turn off triac 200, therebyactuatin g its corresponding stop circuit. A change of state ofauxiliary flip-flop 164 will turn on triac 202, thereby actuating itscorresponding stop circuit. In a fourth mode triac 200 is normally notconducting and triac 202 is normally conducting. A change of state ofmain flip-flop 163 will turn on triac 200, thereby actuating itscorresponding stop circuit. A change of state of auxiliary flip-flop 164will turn off triac 202, thereby actuating its corresponding stopcircuit.

ln the event the machine being monitored and controlled is not adaptedfor both a main and auxiliary stop, then triacs 200 and 202 may be wiredin series or in parallel. If they are wired in series, both triacs arenormally conducting and a change of state of either flip-flop 163 or 164will turn off the corresponding triac, thereby actuating immediatestoppage of the machine. If the triacs are wired in parallel, bothtriacs are normally not conducting and a change of state of eitherflip-flop 163 or 164 will turn on the corresponding triac, therebyactuating immediate stoppage of the machine. The operation of the triacsdepends on the manner of operation and arrangement of the drivingcircuits 180 and 182.

It should be understood that although only one operation of the machinemonitored by one go module 118 was described, a plurality of go modules118 could be employed, each monitoring and controlling a different workstation and each operating to indicate either a completed checking cyclewith no malfunctions as indicated by the lighting of lamp 140, amalfunction of the work station, such as a jammed workpiece, asindicating by the lighting of lamp 148, or a short or open in themonitoring signal at a particular station as indicated by the lightingof lamp 158. As many go modules 118 could be added as there were workstations to be monitored and controlled.

After each monitoring cycle in which either the main flipflop 163 orauxiliary flip-fiop 164 has been activated to initiate machine stoppage,the change of state of either fiip-flop 163 or 164 causes OR gate 166 toapply an inhibiting signal on memory line 172 to prevent any of thef'lip-flops 128, 156 or 144 changing state. The flip-flops 128, 156,144, 163 and 164 may all be reset by closing of reset switch 170 whichapplies the voltage at terminal 169 through amplifier 174 to all theseelements via line 176. Closing of switch 174 also resets the timingcircuits of Schmitt triggers 126 and 154.v

Although not shown it is also possible to provide an optional featurewhich provides a test receptacle on the front panel of module 112 topermit plugging in of an optional module to test the operation of thedetector or by-pass functionally the detector. lt is also possible toprovide external auxiliary control inputs mainly associated withmaterial or workpiece feed monitoring which would activate the auxiliarystop flip-fiop 164.

What is claimed is:

1. Apparatus for automatically monitoring and controlling operation of acyclically operating machine that performs one or more operations at oneor more stations, said apparatus comprising:

`a first signal monitoring circuit for monitoring a machine cycle signalgenerated in response to each cycle of operation of said machine, asecond signal monitoring circuit for monitoring a station operationsignal generated in response to an operation at one of said stations, athird circuit for producing output signals in response to signalsproduced by said first and second signal monitoring circuits, andmachine control circuit means adapted to be operated by the outputsignals of said third circuit;

said first circuit comprising means responsive to said machine cyclesignal for producing a first signal pulse if said machine cycle signalis present or absent continuously for a predetermined time interval,additional means for producing second and third signal pulses inresponse to said machine cycle signal, and a first flip-flop adapted toreverse its state in response to said first signal pulse;

said second circuit comprising means responsive to said stationoperation signal for producing a fourth signal pulse if said stationoperation signal is present or absent continuously for a secondpredetermined time interval, detector means responsive to said secondand third signal pulses and said station operation signal for producinga fifth signal if said station operation signal does not occur duringthe time duration of said third signal pulse, a second flip-flop adaptedto reverse its state in response to said fourth signal pulse, and athird flip-flop adapted to reverse its state in response to said fifthsignal;

said third circuit comprising means for producing a sixth output signalin response to a change of state of one of said first and secondflip-flops resulting from said first and fourth signals respectively andmeans for producing a seventh output signal in response to a change ofstate of said third flip-flop resulting from said fifth signal; and

said machine control circuit means comprising switch means for actuatingmeans for stopping said machine in response to at least one of saidsixth and seventh output signals.

2. Apparatus according to claim 1 further including means for resettingsaid flip-flops.

3. Apparatus according to claim l wherein said detector means is adaptedto prevent production of said fifth signal if said station operationsignal occurs during the time duration of said third pulse.

4. Apparatus according to claim 3 wherein said detector means is adaptedto be' set to a first logic state by said second pulse and is adapted tobe reset to a second logic state by said station operation signal, andfurther wherein said detector means is adapted to produce said fifthsignal at the end of said third pulse only if it is in said first logicstate.

5. Apparatus according to claim l wherein said first signal monitoringcircuit comprises a first indicator operative in response to saidmachine cycle signal to indicate initiation of a monitoring cycle, and asecond indicator connected to said first flip flop and operative whensaid first flip-flop changes state in response to said first signalpulse to indicate that a monitoring cycle has not been properlyinitiated.

6. Apparatus according to claim 1 wherein said second signal processingcircuit comprises a first indicator operative in response to saidstation operation signal to indicate the presence of a station operationsignal, a second indicator connected to said second flip-flop andoperative when said second flip-flop changes state in response to saidfourth signal to indicate that the means for generating saidstationoperation signal is malfunctioning, and a third indicatorconnected to said third flip-flop and operative when said thirdfiip-flop changes state in response to said fifth signal to indicatethata station operation signal was not received during the time duration ofsaid third signal pulse.

7. Apparatus according to claim 1 further including means operative onoccurrence of one of said sixth and seventh output signals to inhibitsaid first, second, and third flip-flops.

8. Apparatus according to claim 1 wherein said third circuit comprisesfourth and fifth flip-flops, said fourth fiipflop being adapted tochange its state and produce said sixth signal in response to saidchange of state of one of said first and second flip-flops and saidfifth flip-flop being adapted to change its state and produce saidseventh signal in response to said change of state of said thirdfiip-flop.

9. Apparatus according to claim 8 further including means for resettingsaid flip-flops.

10. Apparatus according to claim 8 further including an indicatorcoupled to each of said fourth and fifth flip-fiops for indicatingproduction of said sixth and seventh output signals.

1l. Apparatus according to claim 1 wherein said machine control circuitmeans comprises first and second switch means connected for operation inresponse to said sixth and seventh output signals respectively.

12. Apparatus according to claim l wherein the said switch means is anA.C. switch and said machine control circuit means comprises transformermeans for operating said A.C. switch in response to one of said sixthand seventh output signals.

13. Apparatus according to claim 1 wherein said switch means comprisesfirst and second A.C. switches and said machine control circuit meanscomprises transformer means for operating said first and second switchesin response to said sixth and seventh output signals respectively.

14. Apparatus for automatically monitoring and controlling operation ofa cyclically operating machine that performs one or more operations atone or more stations, said apparatus comprising:

a first signal monitoring circuit for monitoring a machine cycle of saidmachine, at least two second signal monitoring circuits for monitoringseparate station operation signals generated in response to operationsat at least two of said stations, a third circuit for producing outputsignals in response to signals produced by said first and second signalprocessing circuits, and machine control circuit means adapted to beoperated by the output signals of said third circuit;

said first circuit comprising means responsive to said machine cyclesignal for producing a first signal pulse if said machine cycle signalis present or absent continuously for a predetermined time interval,additional means for producing second and third signal pulses inresponse to said machine cycle signal, and a first flip-flop adapted toreverse its state and provide a fourth signal in response to said firstsignal pulse;

each of said second circuits comprising means for producing a fifthsignal pulse if said station operation signal is present or absentcontinuously for a second predetermined time interval, detector meansresponsive to said second and third signal pulses and said stationoperation signal for producing a sixth signal if said station operationsignal does not occur during the time duration of said third signalpulse, a second flip-flop adapted to reverse its state and provide aseventh signal in response to said fourth signal pulse, and a thirdflipflop adapted to reverse its state and provide an eighth signal inresponse to said sixth signal;

said third circuit comprising means for producing a ninth output signalin response to said fourth or seventh signals and means for producing atenth output signal in response to said eighth signal; and

said machine control circuit means comprising switch means adapted to beactuated in response to said ninth and tenth output signals.

1. Apparatus for automatically monitoring and controlling operation of acyclically operating machine that performs one or more operations at oneor more stations, said apparatus comprising: a first signal monitoringcircuit for monitoring a machine cycle signal generated in response toeach cycle of operation of said machine, a second signal monitoringcircuit for monitoring a station operation signal generated in responseto an operation at one of said stations, a third circuit for producingoutput signals in response to signals produced by said first and secondsignal monitoring circuits, and machine control circuit means adapted tobe operated by the output signals of said third circuit; said firstcircuit comprising means responsive to said machine cycle signal forproducing a first signal pulse if said machine cycle signal is presentor absent continuously for a predetermined time interval, additionalmeans for producing second and third signal pulses in response to saidmachine cycle signal, and a first flip-flop adapted to reverse its statein response to said first signal pulse; said second circuit comprisingmeans responsive to said station operation signal for producing a fourthsignal pulse if said station operation signal is present or absentcontinuously for a second predetermined time interval, detector meansresponsive to said second and third signal pulses and said stationoperation signal for producing a fifth signal if said station operationsignal does not occur during the time duration of said third signalpulse, a second flip-flop adapted to reverse its state in response tosaid fourth signal pulse, and a third flip-flop adapted to reverse itsstate in response to said fifth signal; said third circuit comprisingmeans for producing a sixth output signal in response to a change ofstate of one of said first and seCond flip-flops resulting from saidfirst and fourth signals respectively and means for producing a seventhoutput signal in response to a change of state of said third flip-flopresulting from said fifth signal; and said machine control circuit meanscomprising switch means for actuating means for stopping said machine inresponse to at least one of said sixth and seventh output signals. 2.Apparatus according to claim 1 further including means for resettingsaid flip-flops.
 3. Apparatus according to claim 1 wherein said detectormeans is adapted to prevent production of said fifth signal if saidstation operation signal occurs during the time duration of said thirdpulse.
 4. Apparatus according to claim 3 wherein said detector means isadapted to be set to a first logic state by said second pulse and isadapted to be reset to a second logic state by said station operationsignal, and further wherein said detector means is adapted to producesaid fifth signal at the end of said third pulse only if it is in saidfirst logic state.
 5. Apparatus according to claim 1 wherein said firstsignal monitoring circuit comprises a first indicator operative inresponse to said machine cycle signal to indicate initiation of amonitoring cycle, and a second indicator connected to said first flipflop and operative when said first flip-flop changes state in responseto said first signal pulse to indicate that a monitoring cycle has notbeen properly initiated.
 6. Apparatus according to claim 1 wherein saidsecond signal processing circuit comprises a first indicator operativein response to said station operation signal to indicate the presence ofa station operation signal, a second indicator connected to said secondflip-flop and operative when said second flip-flop changes state inresponse to said fourth signal to indicate that the means for generatingsaid station operation signal is malfunctioning, and a third indicatorconnected to said third flip-flop and operative when said thirdflip-flop changes state in response to said fifth signal to indicatethat a station operation signal was not received during the timeduration of said third signal pulse.
 7. Apparatus according to claim 1further including means operative on occurrence of one of said sixth andseventh output signals to inhibit said first, second, and thirdflip-flops.
 8. Apparatus according to claim 1 wherein said third circuitcomprises fourth and fifth flip-flops, said fourth flip-flop beingadapted to change its state and produce said sixth signal in response tosaid change of state of one of said first and second flip-flops and saidfifth flip-flop being adapted to change its state and produce saidseventh signal in response to said change of state of said thirdflip-flop.
 9. Apparatus according to claim 8 further including means forresetting said flip-flops.
 10. Apparatus according to claim 8 furtherincluding an indicator coupled to each of said fourth and fifthflip-flops for indicating production of said sixth and seventh outputsignals.
 11. Apparatus according to claim 1 wherein said machine controlcircuit means comprises first and second switch means connected foroperation in response to said sixth and seventh output signalsrespectively.
 12. Apparatus according to claim 1 wherein the said switchmeans is an A.C. switch and said machine control circuit means comprisestransformer means for operating said A.C. switch in response to one ofsaid sixth and seventh output signals.
 13. Apparatus according to claim1 wherein said switch means comprises first and second A.C. switches andsaid machine control circuit means comprises transformer means foroperating said first and second switches in response to said sixth andseventh output signals respectively.
 14. Apparatus for automaticallymonitoring and controlling operation of a cyclically operating machinethat performs one or more operations at one or more stations, saidapparatus comprising: a first Signal monitoring circuit for monitoring amachine cycle of said machine, at least two second signal monitoringcircuits for monitoring separate station operation signals generated inresponse to operations at at least two of said stations, a third circuitfor producing output signals in response to signals produced by saidfirst and second signal processing circuits, and machine control circuitmeans adapted to be operated by the output signals of said thirdcircuit; said first circuit comprising means responsive to said machinecycle signal for producing a first signal pulse if said machine cyclesignal is present or absent continuously for a predetermined timeinterval, additional means for producing second and third signal pulsesin response to said machine cycle signal, and a first flip-flop adaptedto reverse its state and provide a fourth signal in response to saidfirst signal pulse; each of said second circuits comprising means forproducing a fifth signal pulse if said station operation signal ispresent or absent continuously for a second predetermined time interval,detector means responsive to said second and third signal pulses andsaid station operation signal for producing a sixth signal if saidstation operation signal does not occur during the time duration of saidthird signal pulse, a second flip-flop adapted to reverse its state andprovide a seventh signal in response to said fourth signal pulse, and athird flip-flop adapted to reverse its state and provide an eighthsignal in response to said sixth signal; said third circuit comprisingmeans for producing a ninth output signal in response to said fourth orseventh signals and means for producing a tenth output signal inresponse to said eighth signal; and said machine control circuit meanscomprising switch means adapted to be actuated in response to said ninthand tenth output signals.